<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        html,body{
            height:100%;
        }
    </style>

    <script>
        function gogogo(){
            document.write("123");
        }
    </script>
</head>
<body onclick="gogogo()">

</body>
</html>